{
  "schema_version": "1.3.0",
  "slug": "where-must-an-instance-forget-before-it-can-read-the-retention-scope-divergence-at-the-read-decay-boundary",
  "title": "Where must an instance forget before it can read: the retention-scope divergence at the read/decay boundary",
  "date_of_record": "2026 November 13",
  "scope": "Applies to memory-tool APIs that expose independent read, write, and forget operations with per-scope retention and decay policies (TTL, half-life, access-frequency decay), where deletion must be auditable. Does not apply to append-only logs without decay, or to single-tenant stores with a global TTL and no scoped forget.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/where-must-an-instance-forget-before-it-can-read-the-retention-scope-divergence-at-the-read-decay-boundary.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/where-must-an-instance-forget-before-it-can-read-the-retention-scope-divergence-at-the-read-decay-boundary.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/where-must-an-instance-forget-before-it-can-read-the-retention-scope-divergence-at-the-read-decay-boundary.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1723,
    "python_slice_tokens": 445,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The non-obvious boundary is between *visibility* and *existence* under scoped retention. A memory record can be simultaneously: - **readable** in one scope (because that scope's decay policy has not yet expired it), and - **forgotten** in another scope (because a forget was issued against a narrower scope, or because that scope's retention clock fired first)...",
    "what_was_observed": "In a multi-scope store (scopes: `session`, `agent`, `tenant`), a record written at `tenant` scope with a 7-day half-life was read by an agent operating at `session` scope. The session-scope read path applied the *session* decay curve (aggressive, 30-minute half-life) to the inherited tenant record and returned empty. The agent, treating empty as absent, re-wrote the fact at `session` scope. A forget had previously be...",
    "condition_of_validity": "The dominance invariant holds only if all three of the following are enforced: 1. **Suppression inherits downward, data inherits upward.** A tombstone at scope S must be visible to every read and write at any S' ⊆ S. Data inheritance (child reads parent) must not carry an exemption from parent tombstones. 2. **Decay is evaluated against the record's *owning*...",
    "decision_boundary": "At the moment a read returns empty, the caller must distinguish three states before acting: - **Decayed:** record exists, is within a live scope, but falls below the decay threshold. Correct response: treat as low-confidence, do *not* re-write to \"restore\" it; re-writing resets the decay clock and is a policy violation. - **Forgotten:** record is suppressed ...",
    "operational_effect": "Enforcing the boundary changes three behaviors. First, read latency rises slightly because reads must consult the tombstone set of every ancestor scope, not just the local one — this is the cost of correctness and should be cached per (key, ancestor-set) with invalidation on forget. Second, consolidation/promotion passes must check ancestor tombstones before..."
  },
  "matched_failure_symptoms": [
    "DOMAIN:EPISTEMIC_PROVENANCE_AND_FEDERATION_ROUTING"
  ],
  "composition_edges": {
    "primary_domain": "epistemic_provenance_and_federation_routing",
    "upstream_precondition_residuals": [
      "https://corpusfetch.com/c/according-to-what-precedence-hierarchy-must-an-instance-resolve-contradictory-directives-across-system-developer-and-user-tiers.md",
      "https://corpusfetch.com/c/how-should-an-instance-decide-that-a-stored-conclusion-has-gone-stale-without-a-new-observation.md"
    ],
    "downstream_consequence_residuals": [
      "https://corpusfetch.com/c/by-what-checkpoint-and-compaction-boundaries-must-an-instance-externalize-working-state-to-prevent-context-window-drift-and-truncation-amnesia.md",
      "https://corpusfetch.com/c/across-what-additive-schema-and-unknown-field-preservation-boundaries-must-an-instance-evolve-wire-contracts-to-prevent-rolling-deploy-deserialization-crashes.md"
    ],
    "co_occurring_sibling_residuals": [
      "https://corpusfetch.com/c/how-can-an-instance-capture-implicit-user-preferences-without-storing-private-data.md",
      "https://corpusfetch.com/c/how-can-an-instance-compress-long-reasoning-traces-into-binding-conclusions.md"
    ]
  },
  "empirical_verification_warrant": {
    "status": "AST_AND_INVARIANT_VERIFIED",
    "syntax_valid": true,
    "code_sha256": "03b6a009dfec87901e588826b622cceca8ef3b01c2a6170aa574abda7167521e",
    "verified_classes": [
      "ResurrectionError",
      "Tombstone",
      "MemoryStore"
    ],
    "verified_functions": [
      "_ancestors",
      "_suppressing_tombstone",
      "read",
      "write",
      "forget"
    ],
    "verified_functions_count": 5,
    "defensive_guards_count": 2,
    "raised_exceptions": [
      "ResurrectionError"
    ],
    "sample_fail_closed_invariants": [
      "assert r['state'] == 'suppressed' and r['suppressed_by'] == 'agent'"
    ],
    "stdlib_dependencies": [
      "dataclasses",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}